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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: Elmer who wrote (38001)	10/2/1998 11:53:00 PM
From: Maxwell	Read Replies (1) \| Respond to of 1571806

Elmer: <<Re: "Can you give me the 6 sigma of speed distribution on Intel 0.25um PII process? " Undoudtedly 6 sigma is waaaaaay outside their scrap limit. They wouldn't even have that data. Are you telling us that AMD ships 6 sigma material?>> You don't understand what I mean. Let me try to explain. When you process a wafer from beginning to end there is always some RANDOM VARIATION from wafer to wafer and process variation across the wafer. The result is that at testing you will see a spread in the speed distribution. This distribution is normal and Guassian (due to Random Process Variation). With a Guassian you can get sigma and 6 sigma represents the speed spread. For example, on Intel 0.25um process if you get 25% 400MHz and with a known sigma you can calculate the % of 350MHz and % of 450MHz. I suspect Intel 6 sigma is about 100MHz since they get anything from 300MHz to 400MHz on their 0.25um process. Yousef can give us better data since he works in photo and controls the poly cds of the PII and CeleronA. Maxwell